Enzymatic Production of Bioactive Protein Hydrolysates from Egg White: Effects of Egg White Protein Pretreatment

Abstract

The use of egg white hydrolysed protein has attracted particular interests as a protein source in human nutrition providing a number of benefits when compared to unhydrolysed protein ingredients. Of high importance is the production of an hydrolysate which contains bioactive peptides and does not have allergen potential to be used as the primary or only source of protein in “infant formula”, diets, or “medical food”. At present, expanded egg white hydrolysates utilization is impeded by inadequate functional properties caused by processing treatments during commercial production that alter egg white proteins` physicochemical properties and nutritional quality, among then the thermal treatment is one of the most damaging to the proteins. Thus, a lot of research works have been performed to investigate the effectiveness of replacing conventional thermal treatment with several non-thermal alternative approaches for improvement the overall process performances of egg white proteins (EWPs) hydrolysis and produce protein solutions with new functional properties. In this study, the effect of ultrasound pretreatment at 27 oC and at atmospheric pressure and of high pressure carbon dioxide processing in the range 10-30 MPa on the enzymatic hydrolysis of EWPs with alcalase has been investigated. As pH seemed to strongly affect the ultrasound induced protein denaturation, the effect of pH during sonication in the range 6.0-10.0 on the egg white susceptibilityto enzymatic hydrolysis has been studied. The functional properties, molecular weight distribution, and antioxidant activity of obtained hydrolysates were also investigated. It appeared that the ultrasound pretreatment resulted in an increase in degree of hydrolysis of the enzymatic reaction while the high pressure carbon dioxide processing showed an inhibition effect on the enzymatic hydrolysis of EWPs to some extent. Antioxidant activity of obtained hydrolysates was improved by ultrasound pretreatment of EGPs at pH 8.3. Thus, the combination of ultrasound pretreatment at pH 8.3 and subsequent enzymatic hydrolysis with alcalase at 50 oC and pH 8.0 could offer a new approach to improve the functional properties of EWPs and their biological activity.